package day0717;

import java.util.Scanner;

//累加和
public class Test1 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n=sc.nextInt();

        int i = 1;
        int sum=0;
        while(i <=  n){
            sum = sum +i;
            i++;
        }


    }
}
